Substituted derivatives of malonic acid useful as stabilizers

ABSTRACT

Derivatives of malonic acid substituted with groups containing a hindered phenol are disclosed. The compounds are stabilizers suitable for stabilizing numerous substrates of organic material subject to oxidative deterioration, in particular polypropylene. Synergistic combinations of these compounds and dialkyl thiodipropionates are disclosed.

O United States Patent [151 3,678,095 Dexter et al. 1 July 18, 1972 [54] SUBSTITUTED DERIVATIVES 0F [56] References Cited MALONIC ACID USEFUL AS UNITED STATES PATENTS STABILIZERS I 3,112,338 11/1963 Smutny et al. ..260/473 R [72] Inventors: Martin Dexter, Briarcliff Manor; John Denon Splvack, Spring Valley, both 01 OTHER PUBLICATIONS I Eggensperger, Heinz et al, Chem. Abst. 71 13810e 1969) [73] Assignee: Gelgy Chemical Corporation, Greenburgh, Gilles, Chem- Abst. 71 1 3 NY. Dexter et al, Chem. Ast. 71 l02930m 1969) 7 970 [22] filed July I 1 Primary Examiner-Lorraine A. Weinberger PP 55'938 Assistant Examiner-John F. Tenapane Rehml us. Application Data Attorney-Karl F. Jorda and Nestor W. Shust [63] Continuation-impart of Ser. No. 616,801, Feb. 17, [57] ABSTRACT Derivatives of malonic acid substituted with groups containing [5 2] U.S. Cl. ..260/473 S, 260/4185, 260/3985, a hin r phenol ar disclosed- The compounds are stabil- 260/590, 260/810, 44/70, 99/163, 252/57 izers suitable for stabilizing numerous substrates of organic [5 1] Int. Cl. ..C07c 69/76 material subject to oxidative deterioration, in particular "[58] Field of Search ..260/473 S, 465 P polypropylene. Synergistic combinations of these compounds and dialkyl thiodipropionates are disclosed.

8 Claims, No Drawings SUBSTITUTED DERIVATIVES OF MALONIC ACID USEFUL AS STABILIZERS THE INVENTION This is a continuation-impart of our copending application Ser. No. 616,801 filed Feb. 17,1967.

Natural or synthetic resins, such as polypropylene and polyethylene, are often subject to oxidative deterioration. Other unstable organic materials, such as synthetic lubricants, hydrocarbons, natural and synthetic rubbers, oils of animal or vegetable origin, and the like are also unstable to thermal or oxidative deterioration. Such materials may also be unstable to ultraviolet or visible light.

It is a principal object of the present invention, therefore, to provide new stabilizers for organic material. It is a further object to provide compositions by incorporating in organic material normally subject to deterioration, stabilizing amounts of a stabilizer as herein described. Other objects of the invention will be apparent from what follows.

It has been found that the compounds ofthis invention are efiective in various organic materials, normally subjectto oxidativedeterioration. The stabilizers of the invention comprise substituted derivatives of malonic acid and related compounds of the formula:

FORMULA I where R and R are alkyl of one to 18 carbon atoms or cycloalkyl of five to 12 carbon atoms. Alkyl of one to eight carbon atoms is preferred and most preferably R and R are tertiary butyl positioned ortho to the hydroxy group.

A is alkylene of one to 12 carbon atoms. It may be branched or straight chain. Preferably it has one to six carbon atoms, and most preferably it is methylene.

B is lower alkylene, i.e., alkylene of one to six carbon atoms, and may be branched or straight chain. Y and U are both m and are or 1 R and R, are phenyl or substituted phenyl; Y is cyano, C,-C alkyl or R1 provided that when Y and Y are carbonyl, R and R may also be amino, C -C alkyl or alkylthioalkyl; provided further that when m is 0 and n is I, Y and R taken together and Y, and K taken together may also be cyano or cyanoloweralkyl; and provided further that when R, is cyano, R and R may also be C -C alkyl or amino.

It is understood that in this application and the appended claims the term alkyl" contemplates both branched and straight chain. Representative of such alkyl groups are thus methyl, ethyl, propyl, i-propyl, n-butyl, s-butyl, t-butyl, octyl, decyl, dodecyl, tetradecyl, octadecyl, and the like.

As previously stated, the compounds of the present invention are useful in the stabilization of organic material normally subject to deterioration. Theefficacy of these compounds is evident for example from the greatly increased stability of polymeric material containing a compound of this invention when subject to oxidative deterioration. In this specification is is understood that polymeric material includes both homopolymeric and copolymeric, such as vinyl resins formed from the polymerization of vinyl halides or from the copolymerization of vinyl halides with unsaturated polymerizable compounds. e.g.. vinylesters, a,B-unsaturated acids, a,,B-unsaturated esters, a,B-unsaturated ketones, afiunsaturated aldehydes and unsaturated hydrocarbons such as butadiene and styrene; poly-a-olefins such as polymethylene, polyethylene, polypropylene, polybutylene, poly-4-methyl pentene-l, polyisoprene and the like, including copolymers of poly-a-olefins; polyurethanes such as are prepared from polyols and organic polyisocyanates; polyamides, such as polyhexamethylene adipamide; polyesters such as polymethylene terephthalates; polymethylmethacrylate; polycarbonates; polyacetals; polystyrene; polyphenylene oxide; polyethyleneoxide; polyacrylics such as polyacrylonitrile; and the like, including mixtures of the foregoing such as those of high impact polystyrene containing copolymers of butadiene and styrene and those formed by the copolymerization of acrylonitrile, butadiene and/or styrene. The preferred polymeric material for stabilization is polypropylene.

Polymeric materials, such as the foregoing, find use as thermoplastic molding or coating agents. Moreover. because of their high dielectric strength and its resistance to water, such materials are particularly useful as insulators or dielectrics in condensers and similar equipment. It is known that these polyolefins, such as polyethylene and polypropylene, are attacked by oxygen, particularly when exposed to the atmosphere and at elevated temperatures. During use or manufacture, for example, the desirable properties of the polyolefins are often impaired by oxidative deterioration. Such degradation causes loss in dielectric properties, discoloration, embrittlement, gelation, and the like. In addition to overcoming these difficulties, the compositions of this invention are also stabilized against degradation caused by heat and light.

The compounds of this invention are also particularly useful in stabilizing lubricating oils of various types including aliphatic esters, polyalkylene oxides, silicones, esters of phosphoric and silicic acids, highly fluorine-substituted hydrocarbons, and the like. Specifically, such aliphatic esters which are usefully stabilized comprise dihexyl azelate, di-(2- ethylhexyl) azelate, di-(3,5,5-trimethylhexyl) glutarate, di- (3,5,5-trimethylpentyl) glutarate, di-(Z-ethylhexyl) pimelate, di-2(2-ethylhexyl) adipate, diisoamyl adipate, triamyl tricarballylate, pentaerythritol tetracaproate, dipropylene glycol dipelargonate, l,5-pentanediol di-2( 2-ethylhexanoate), and the like. Other specific lubricants include polyisopropylene oxide, polyiospropylene oxide diether, polyisopropylene oxide diester, and the like, as well as methyl silicone, methylphenyl silicone, tetraisoctyl silicate, etc. and fluorinated oils, such as perfluorohydrocarbons.

The present invention also relates to the stabilization of fatty materials, including oils of animal or vegetable origin, which tend to deteriorate on standing or exposure to atmospheric oxygen. Also within the scope of the invention are saturated and unsaturated hydrocarbons which tend to deteriorate on storage and use, such as for example, gasolines, jet fuels, diesel oils, mineral oils, and the like. Such hydrocarbons are protected against gum formation, discoloration and other deterioration with the stabilizers of the present invention. Greases and cutting oils may also be stabilized in the same fashion.

These compounds are especially useful in stabilizing polyolefinic material, particularly polypropylene. Fatty acids, such as stearic acid, resins such as acrylonitrilebutadienestyrene (ABS) terpolymers and polyphenylene oxide, cyclohexene and synthetic oils, such as trimethylolpropane esters of acetic acid, n-valeric acid, hexanoic acid, caprylic acid, pelargonic acid, 2-ethylhexanoic acid, Z-ethylpropanoic acid, and 2-methylpentanoic acid, and mixtures thereof are also very effectively stabilized with the foregoing stabilizers.

The stabilizers of this invention are also useful in stabilizing rubber, e.,g. artificial and natural rubber. Other examples of rubber which may be stabilized according to the invention include polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, butyl rubber, nitrile rubber, neoprene rubber and blends of artificial rubber with natural rubber, such as for example natural rubber with polybutadiene rubber. Broadly contemplated is the stabilization of any rubber normally subject to degradation.

Particularly preferred stabilizers of the invention are di- (4'tertiary octylphenyl)-2,2-bis-(3",5" di-t-butyl-4"-hydroxybenzyl) malonate, diphenyl-2,2-bis(3,5' di-t-butyl-4- hydroxybenzyl) malonate and di-4'-t-butylphenyl-2,2-bis (3",5" -"""'"'"4"-hydroxybenzyl) malonate.

In general, stabilizers of the invention are employed in a concentration of from about 0.001 percent to about percent by weight, preferably from about 0.1 percent to about 1 percent by weight. The specific concentration employed varies with the unstabilized material and the specific stabilizer. When mixtures of two or more stabilizers are employed in an unstable material, usually the total amount of added stabilizer does not exceed 10 percent of the total stabilized material.

The stabilizer compounds of this invention may be used also to stabilize organic material in combination with other additive agents, such as e.g. antioxidants, antiozonants, pourpoint depressants. corrosion and rust inhibitors, dispersing agent, chelating agents, surface active agents, demulsifiers, antifoaming agents, carbon black, accelerators, plasticizers, color stabilizers, heat stabilizers, ultraviolet absorbers, dyes and pigments, fillers, etc.

Merely by way of illustration, the following reaction schemes may be employed in preparing the compounds of this invention. Alternative methods will be readily apparent to those skilled in the art.

+ 2 Sodium Methylato (came I a)a As mentioned, the stabilizers employed in this invention may be used alone or in combination with other stabilizers or additive materials. Especially useful in certain cases is the stabilizer di-lauryl-beta-thiodipropionate. Special mention also is made of di-stearyl-beta-thiodipropionate.

Broadly, compounds of the formula wherein R is an alkyl group having from six to 24 carbon atoms and X is an integer from 1 to 6, are useful stabilizers in combination with the compounds of the FORMULA I of the invention.

In this specification, the term stabilization" includes protection not merely against oxidative deterioration but also protection against deterioration caused by thermal effects, visible and/or ultraviolet radiation, etc. Thus the stabilizers of the invention are contemplated as acting to protect unstable materials not only against oxidative deterioration but also against other types of deterioration such as thermal degradation or degradation caused by visible and/or ultraviolet light, particle radiation, etc.

The compositions are prepared by a number of means, depending on the substrate. For example, the instant stabilizers can be mixed into liquid substrates and can be milled into thermoplastic substrates. For addition to varnishes, the stabilizer can be dissolved in a co-solvent and this added to the varnish. As mentioned hereinbefore and exemplified hereinafter, levels of the stabilizers in the substrate may vary considerably depending on the particular end application, degree of protection desired, variations in the substrate, and presence of synergizing stabilizers (ultraviolet absorbers, dialkyl thiodipropionates, and the like).

Selecting the proper use level is well within the capabilities of those skilled in the art. Addition of the instant stabilizers imparts little or no color to most substrates and, after formulation, they are characterized by substantial ability to retain good color under processing conditions and weathering.

The instant invention provides polyolefin compositions protected against thermal and oxidative degradation during processing. It provides minimized melt-flow drift, and extends the service life of finished articles. Particularly noteworthy are the instant compositions excellent color retention under prolonged heat or light exposure, and their resistance to extraction by boiling water and alkaline detergents.

The following examples describing certain representative embodiments of this invention will serve to further illustrate the nature of the invention. It is to be understood that the examples are merely illustrative and intended to enable those skilled in the art to practice the invention in all of the embodii'nents flowing therefrom and do not in any way limit the scope of the invention defined in the claims.

In the examples, parts are by weight unless otherwise indicated and the relationship between parts by weight and parts by volume is as that between grams and cubic centimeters.

EXAMPLE 1 3 ,3-Bis-( 3 ,5 '-di-t-butyl-4'-hydroxybenzyl)-2,4-pentanedione 5.1 parts of sodium (0.22 moles) is dissolved in 100 parts of methanol by heating, finally at reflux temperatures until dissolved. The sodium methylate solution is cooled to 15 C. and 10.0 parts of 2,4-pentanedione (0.10 moles) added. A heptane solution of 3,S-di-t-butyl-4-hydroxybenzyl chloride (83 parts, 61.1 percent, 0.20 moles) is added dropwise to the methanolic solution over a period of 45 minutes at C., the resulting reaction mixture being stirred at room temperature for 2 hours, and at 45 50 C. for 1 hour. The reaction mixture is made acid with about 5 parts of glacial acetic acid, and the solvents removed by distillation at mm. Hg. pressure. The residue is triturated with 200 parts by volume of hexane, washed with hot water and dried in the vacuum oven at 100 mm. Hg. pressure at 70 C. for 16 hours. 3,3-bis-(3,5'-

di-ti-butyl-4-hydroxybenzyl)-2,4-pentanedione is obtained in the form of white crystals melting at 155 C. after two crystallizations from isopropanol.

Analysis: Calculated for C :,,H 0 Mol. Wt. 136.7

C H 78.31% 9.77% Found: 78.06% 9.79%

EXAMPLE 2 (3 ,5 'di-t-butyl-4'-hydroxyphenyl)-Cyanopimelonitrile 24.5 Parts of 3,5-di-t-butyl-4'-hydroxybenzyl cyanide (0.10 moles) is dissolved at 40 C. in 150 parts of t-butanol containing 3.36 parts (0.03 moles of potassium-t-butoxide to give a clear green solution. 10.6 parts of acrylonitrile is then added dropwise over a period of 15 minutes and the reaction mixture heated a reflux for 5 hours during which time the color changes to yellowish brown. The reaction mixture is cooled to 30 C. 100 parts of 10 percent acetic acid is added and the reaction mixture cooled to 10 C. The precipitated crystals are filtered, washed with water and dried. The crystals melt at 124 126 C. Recrystallization from a solvent mixture of 75:25 t-butanol-isopropanol yields white crystals melting at l24126 C.

Analysis: Calculated for C H 0N C H N 75.17% 8.31% 11.95% Found: 75.57% 7.98% 12.20%

EXAMPLE 3 Dimethyl 4-(3',5'-di-t-butyl-4'-hydroxyphenyl)-4- Cyanopimelate 17.5 parts of 4-(3,5'-di-t-butyl-4-hydroxyphenyl)-4- cyanopimelonitrile is dissolved in parts of methanol and then cooled to -10 C., the fine suspension being saturated with gaseous hydrogen chloride at -5 to 0 C. over a period of 40 minutes. The reaction mixture is then stirred and heated at reflux for 30 minutes. The resultant crystal slurry is then poured onto 500 parts of ice. After the ice has melted the crystals are filtered, washed with water, then redispersed in water and heated on the steam bath for 1 V2 hours. The disper sion is then cooled, the precipitate being filtered and taken up in ether. The ether solution is then washed with sodium bicarbonate and dried over sodium sulfate. The ether solution is concentrated in vacuum to yield the product as a crystalline residue. The residue is than recrystallized from n-hexane yielding white crystals melting at l 10-1 12 C.

Analysis: Calculated for C ,H O N C H N 69.03% 8.44% 3.35% Found: 69.14% 8.45% 3.33%

EXAMPLE 4 Di-Phenyl-2,2-Bis-( 3 ,5 '-di-t-butyl-4 -hydroxybenzyl) Malonate Forty-seven grams of phenol, 100 ml. of hexene and 35 g. of malonyl chloride were refluxed for one hour, at the end of which time hydrogen chloride evolutions had practically ceased. The reaction mixture was cooled to room temperature and washed, first with water, then with a dilute aqueous solution of sodium bicarbonate and then again with water and dried over sodium sulfate. After filtration and evaporation of the solvent, the product, diphenyl malonate, crystallized out. It was purified by recrystallization from aqueous ethanol. M.P. 52 C.

A portion of the diphenyl malonate so prepared (0.25 mols) is suspended in toluene, and cooled, with stirring, to 10 C. Sodium amide (0.55 mols) is then added and within 90 minutes a 45 percent hexane solution containing 0.55 mols of 3,5,-di-tert-butyl-4-hydroxybenzyl chloride is added at the same temperature. The mixture is stirred at ambient temperature for 1 hour, heated to 55 C. and kept at that temperature for another hour. The mixture is extracted three times with water and the hexane solution is evaporated to dryness under vacuum. The residue is treated with hot methanol, filtered, and washed with hexane and then with water. The resulting diphenyl-2,2-bis (3,5'-di-t-butyl-4-hydroxybenzyl) malonate has a melting point of C.

EXAMPLE 5 Di-3 -Methylphenyl-2,2-Bis-( 3 ,5 '-d-t-butyl-4' hydroxybenzyl) Malonate Following the procedure of Example 4, di-3'-methylphenyl malonate is prepared by the reaction of m-methylphenol with malonyl chloride. The resulting malonate is then reacted with 3,5-di-t-butyl-4-hydroxybenzyl chloride to give di-3'- methylphenyl-2,2-bis(3 ",5 '4' '-hydroxybenzyl) malonate, mp. 146C.

EXAMPLE 6 The melting points of these derivatives are indicated in Table A below.

Di-4'-t-octylphenyl-2,2-Bis-(3",5"-di-t-butyl-4"- TABLE A hydroxybenzyl) Malonate Into a 1.5 liter sulfonation flask are put 103g (1 mol) of 5 Example R2 Bland '5? finely divided malonic acid, 427 g (2.06 mol) of a 4-t-octylphenol (*4-(l,l,3,3-tetramethylbutyl) phenol) and 4 ml 7 y- -B yl. see butyl 132 dimethylforrnamide in 300 g of hexane, and heated with slow stirring to a temperature of 65-70 C. At that temperature 10 8 over about 3 hours 262 g (2.2 mol) of thionyl chloride are t'bmyl 182 added dropwise under the surface of the reaction mixture. Cvaseous HCl and S0 are given oft and absorbed in an absorp- 9 "do isoamyl 135 tron tower. The reactants are stirred for a further 2 hours at 65-70 C. and treated once again with 4 ml of dimethylforma- 1 mide. The reactants are stirred for a further hour at 70-75 C. 10 "d t-hexyl' 14a The original suspension during this time changes to a redbrown solution and gas evolution almost ceases. The solution H; is cooled to room temperature and treated with 150 g of petroleum ether. It is cooled without stirring to 0 C. and held 11 -hexyl' 150 at this temperature for 2 hours. The product deposits in crystalline form. The reaction mixture is filtered off with suc- 12 d d tion and the brown residue is washed with petroleum ether o and dried with suction. The product is then dried under vacuum for 5 hours at 70 C. A yield of 390 g of di-4-t-oc- 1 "do G phenyl 2m tylphenyl malonate (81 percent of theoretical based on marinic acid) is obtained, practically colorless crystals, M.P. 109-1 10 C, m M yl" t-oclyl 170 A portion, 120 g (0.25 mol) of the ester so made and I70 g toluene were cooled to l0 C. Under stirring there was added 15 M th 1 d at this temperature, dropwise over a period of 90 minutes, a e y 185 freshly prepared solution of sodium methylate in methanol and simultaneously, through a second dropping funnel, 134 g (0.55 mol) of benzylchloride, in the form of a percent solu- C-CCC tion in an aliphatic hydrocarbon solvent. There should always be a slight excess of alcoholate present, recognizable by the red color of the reaction mixture. (An excess of benzylchloride leads to a reversible change of the solution EXAMPLE l6 l ie r z o n is exothermic and it must therefore be well Unsmbilized polyqropylene l is cooled. During the dropwise additions the deposition of NaCl lhorouhly blended wlth 1% by of 331x543 begins; however the deposit remains always stirrable. After l' I P and 'F the entire dropwise addition of the sodium methylate solution dnaury! fi'thlopmplonate T materlal the color changes to yellow with the dropwise addition of the "l' on a "Q at 182 f 5 mmutes' after remainder ofthe benzylchloride Solution 45 which time the stabilized polypropylene rs sheeted from the After the dropwise addition has been completed, the cooland *P' to Cool ing bath is removed and the mixture is stirred l hour at room The mlned PlYPmPY1em Sheet thenFm Small p'eces temperature. It is then warmed to C. and stirred a further and pressed for 7 mmutFs on a hydrauhc press at 2180 and hour at this temperature. Then a few ml of acetic acid are ZOOOPOUPdS Per quare mch Pressure-The resultant Sheet of added to give a pH of about The reaction mixture is the 50 25 mil thickness is then tested for resistance to accelerated heated to C. and the solvent is completely drawn off under H force? draft at The resultant Composmon vacuum The remaining redbmwn n is dissolved in hot is stabilized against oxrdatrve deterioration for 425 hours. Unmethanol, the solution cooled to 0-3 and kept at this tem- Stabllfzed Polypropylene deterforaies Y 3 perature for about 5 hours. The reaction mixture is filtered 55 hke manner asthe foregfnng P was p f under vacuum and the yellow residue is washed with 2 porhaving P y Weight y 4 i tions of hexane and then with water, after which the product y y y y y p and 05% DLTDP- displays only a m yellow tinga The product i dried f 3 Sheets made from this composition were stabilized for H0 hours under vacuum at 70 C The yield is 190 g of di-4"-t-oct l henyl-2,2-bis (3',5'-dit-but l-4'-h drox be I) ni a lonate, M.P. l75-l76 C. This is 83 p rcent ot he 6O EXAMPLE l7 theoretical, based on the malonic estef- The compounds made in Examples 5, 7 and 9 were tested After recrystallization groin, colorless crystals, for their ability to stabilize polypropylene using the following l79-80bL C., are obtained. technique:

One hundred (l00) parts by weight of polypropylene were EXAMPLES L15 thoroughly mixed with 0.2 parts of the compound to be tested, Following the procedure of Example 4, using appropriately or with 0.1 part of the test compound and 0.3 parts of dilaurylsubstituted phenols and 4-hydroxybenzyl chlorides various thiodipropionate (DLTDP), processed in a Brabender plastomalonate esters of the general formula graph at 200 C. for 6 minutes and pressed into 40 mil sheets from which 0.4X7 inch test specimens are cut out. RI R Three test specimens at a time are placed on small steel I C 0 0 R hooks in each of two forced draft ovens maintained at 149 1- 0 0.5 C. and 135 105 C. respectively. The specimens are ex- 1 amined regularly and the exposure time in days until visual C O O degradation occurs, is noted.

In a second, accelerated testing procedure, bundles of small 2. A compound claimed in claim 1 wherein R is rectangular plates cut from the 40 mil sheets, four or five at a time are sliced into sections 1 mil thick using a heavy microtome with a D-type knife. Approximately 80-100 I cuttings are sandwiched between two steel screens which are 5 CH? then mounted on a rack in one or the other of two forced draft ovens maintained at 147 and l35 C. respectively. The onset 1 of embrittlement is easily recognized upon tapping the sample (screen) by hand and is taken as the point of failure. 3. A compound claimed in claim 1 wherein R and R are In a somewhat different test, small rectangular plates cut tertiary butyl. from 40 mil sheets were exposed in a Xenotest" irradiation 4. A compound claimed in claim 2 where R and R are terapparatus and inspected for color after 200 and 500 hours irtiary butyl. radiation. 5. A compound selected from the group consisting of di-m- The results of these tests are given in Table B. methylphenyl-2,2,bis(3,5-di-t-butyl-4-hydroxybenzyl) TABLE B Oven aging Color of 40- I Color of 40- mil specimen 40-mll specil-mll cutmil specimen during Xenomens, hours tings, hours during oven test exposure, ataging, afterafter- Initial Fail 200 500 Sample Stabilizer system compound of- 135 0. 149 0. 135 C. 147 C. color fidays ure hours hours 1 Example No. 6, 0.2 part/100 parts resin 2, 800 360 570 110 4-5 3-4 3 5 5 2.. Example N0. 6, 0.1 part with 0.3 part DLTDP/lOO parts resin-.- 3,800 800 670 150 5 4-5 2 4-5 45 3 Example No. 4, 0.2 part/100 parts resin 2, 280 290 225 45 4 3 3 4 5 4.. Example No. 4, 0.1 part with 0.3 part DLDTP/lOO parts resin 3, 240 790 240 65 5 4 3 3 3-4 5.- Example No. 8, 0.2 part/100 parts resin 3, 000 336 550 72 3-4 3 3-4 5 5 6 Example No. 8, 0.1 part with 0.3 part DLTDP/lOO parts resm 4,260 840 550 96 5 3-4 23 5 what i l i d is; malonate; di-4 -sec-butylphenyl-2,2-bis-( 3",5"-di-t-butyl-4"- 1. A compound of the formula hydroxybenzyl) malonate; di-4-isoamylphenyl-2,2-bis (3 ,5

-di-t-butyl-4"-hydroxybenzyl)malonate; di-4-t-hexylbenzyl- R; O R 2,2,-bis( 3",5"-di-t-butyl-4"-hydroxybenzyl) malonate; di-2- 3 methyl-4'-t-hexylbenzyl-2,2-bis (3",5"-di-t-butyl-4"-hydrox- HO- -CH -C-R ybenzyl) malonate; di-4-cyclohexylbenzyl-2,2-bis( 3",5"-dit-butyd:4";hydroxybeniyl) malonate; d|-4'-phenylphenyl-2,2 R 1 [1 bis (3 ,5 -di-t-butyl-4 -hydroxybenzyl) malonate; di-4 -t-oc- 0 tylphenyl-2,2-bis( 3 't-butyl-S -methyl-4' '-hydroxybenzyl) wherein malonate; di-4"t-octylphenyl-2,2,bis (3",5 dimethyl-4"- R, and R are alkyl groups having from one to eight carbon hydroxybenzyl) malonate; di-4'-t-octylphenyl-2,2-bis (3",5"- atoms, 40 di-t-butyl-4"-hydroxybenzyl) malonate; diphenyl-2,2-bis R and R are phenyl, mono or dialkyl substituted phenyl, (3'5' 4-hydroxybenzyl) malonate; di-4'di-t-buthe alkyl substituents having up to eight carbon atoms or tylphenyl-2,2-bis (3,5" -di-t-butyl-4"-hydroxybenzyl) cyclohexyl substituted phenyl, and malonate.

R lS cyano, an alkyl group of from one to four carbon atoms 6, Di-4'-t-oct l henyl-2,2-bis-( 3",5"-di-t-butyl-4'-hydroxor ybenzyl) malonate.

7. Diphenyl-2,2-bis( 3 ,5 -di-t-butyl-4'-hydroxybenzyl) malonate. CH2- -0 H 8. Di-4'-t-butylphenyl-2,2-bis-( 3 ,5 '-di-t-butyl-4' -hydroxybenzyl) malonate.

wherein R, and R are as defined above.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,678,095

DATED 1 July 18, 1972 lN ENTO 1 Martin Dexter and John Denon Spivack It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 41, "U should read Y Column 1, line 46, Y should read R Column 6, line 75, (3" ,5"4"hydroxybenzyl) should read (3",5"-ditbutyl4"hydroxybenzyl) Column 7, line 64, "l7980bLC.,' should read Column 8, Example 7 of Table A, "see butyl" should read sec butyl Signed and Scaled this Thirteenth Day Of September 1977 [SEAL] Attest:

RUTH C. MASON LUTRELLE F. PARKER Attesting Officer Acting Commissioner of Patents and Trademarks UNTTED STATES PATENT oTTTcE CERJ'HMQATE @F CQRRECTWN Patent No. 3,678,095 Dated July 18, 1972 Inventor(s) rtin Dexter 8t 8.].

It is certified that error appears in the above-identified patent and that said Letters Patentare hereby corrected as shown below:

On the cover sheet [73] thename of theassignee should read CIBA-GEIGY Corporation Signed and sealed this 19th day ofD-cember 1972.

(SEAL) Attest:

EDWARD MTLETCmm-JR; ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DC GOE'IG-POQ U.S. GOVERNMENT PRINTING OFFICE: I969 0-366-334,

FORM Po-1o5o (10-69) 

2. A compound claimed in claim 1 wherein R5 is
 3. A compound claimed in claim 1 wherein R1 and R2 are tertiary butyl.
 4. A compound claimed in claim 2 where R1 and R2 are tertiary butyl.
 5. A compound selected from the group consisting of di-m-methylphenyl-2,2,bis(3'' ,5''-di-t-butyl-4''-hydroxybenzyl) malonate; di-4''-sec-butylphenyl-2,2-bis-(3'''' ,5''''-di-t-butyl-4''''-hydroxybenzyl) malonate; di-4''-isoamylphenyl-2,2-bis (3'''' ,5''''-di-t-butyl-4'''' -hydroxybenzyl)malonate; di-4''-t-hexylbenzyl-2,2,-bis(3'''' ,5''''-di-t-butyl-4''''-hydroxybenzyl) malonate; di-2''-methyl-4''-t-hexylbenzyl-2,2-bis (3'''' ,5''''-di-t-butyl-4''''-hydroxybenzyl) malonate; di-4''-cyclohexylbenzyl-2,2-bis(3'''' ,5''''-di-t-butyl-4''''-hydroxybenzyl) malonate; di-4''-phenylphenyl-2,2-bis (3'''' ,5''''-di-t-butyl-4''''-hydroxybenzyl) malonate; di-4''-t-octylphenyl-2,2-bis(3''''t-butyl-5''''-methyl-4''''-hydroxybenzyl) malonate; di-4''-t-octylphenyl-2,2,bis (3'''' ,5'''' dimethyl-4''''-hydroxybenzyl) malonate; di-4''-t-octylphenyl-2,2-bis (3'''' ,5''''-di-t-butyl-4'''' -hydroxybenzyl) malonate; diphenyl-2,2-bis (3'' 5''-di-t-butyl-4''-hydroxybenzyl) malonate; di-4''di-t-butylphenyl-2,2-bis (3'''' ,5'''' -di-t-butyl-4''''-hydroxybenzyl) malonate.
 6. Di-4'' -t-octylphenyl-2,2-bis-(3'''' ,5''''-di-t-butyl-4''-hydroxybenzyl) malonate.
 7. Diphenyl-2,2-bis(3'',5''-di-t-butyl-4''-hydroxybenzyl) malonate.
 8. Di-4''-t-butylphenyl-2,2-bis-(3'''' ,5''''-di-t-butyl-4''''-hydroxybenzyl) malonate. 